Later Wednesday, the National Enquirer and New York Daily News reported that Limbaugh was under investigation in Florida for illegally buying and abusing prescription painkillers.

"My comments this past Sunday were directed at the media and were not racially motivated. I offered an opinion," Limbaugh said in a statement released by ESPN. "This opinion has caused discomfort to the crew, which I regret.

ESPN

Limbaugh

"I love NFL Sunday Countdown and do not want to be a distraction ... Therefore, I have decided to resign," he said.

Limbaugh on Thursday said he resigned to protect network employees from the uproar over critical comments he made about McNabb.

"The great people at ESPN did not want to deal with this kind of reaction," a relaxed Limbaugh told the National Association of Broadcasters at its convention in Philadelphia on Thursday. "The path of least resistance became for me to resign."

Limbaugh had thought about the issue the night before making the comments, he said. He said he was used to scrutiny after 15 years in radio and expects to get attention.

"I figured if I'm going to do this (the ESPN show) I should be who I am," he said.

About a half-dozen people protested outside the convention.

"We accept his resignation and regret the circumstances surrounding this," said George Bodenheimer, president of ESPN and ABC Sports.

Limbaugh said Sunday that McNabb received undeserved credit for his team's success that came from media outlets with "social concern" and "very desirous that a black quarterback do well."

McNabb, who was runner-up for the MVP award in 2000 and has led the Eagles to two straight conference title games, said Wednesday, "I'm sure he's not the only one that feels that way. But it's somewhat shocking to actually hear that on national TV." McNabb scoffed at the notion of preferential media treatment: "A free ride from the media in Philadelphia? That's a good one."

McNabb said an apology from Limbaugh "would do no good" because his comments "obviously" were premeditated.

Limbaugh was supposed to bring a buzz to Countdown, which Sunday drew about 2.1 million households, its biggest audience in seven years. And that buzz got louder: Two Democratic presidential candidates, Wesley Clark and Howard Dean, called Wednesday for ESPN to fire Limbaugh.

Former San Diego Chargers star Kellen Winslow, spokesman for a group that monitors racial issues in the NFL, called the resignation "great news. Now, ESPN can get back to covering football."

Limbaugh, on his national radio show Wednesday, said, "This is such a mountain out of a molehill. There's no racism here. There's no racist intent whatsoever."